The overall objective of the program project is to develop HIV- vaccines suitable for human use. Once optimal HIV-1 immunogens, adjuvants, carriers, and immunization protocols have been determined in preliminary studies in rhesus monkeys, the specific aims of this research project are to assess their efficacy in chimpanzees through their capability to induce humoral and cell-mediated immune responses in these animals and to prevent infection following a live HIV-1 challenge. Chimpanzees will be immunized at 0, 1, and 6 months. If they respond with good humoral and cell-mediated immune responses as assayed by enzyme linked immunoassay, neutralization assay, antibody dependent cellular cytotoxicity, Western blot, radioimmunoprecipitation, lymphocyte blastogenesis, and cytotoxic T lymphocytes, they will be challenged i.v. 2 weeks later with 100 TCID50 of HIV-1. Besides following their immune responsiveness, their status will be assessed by HIV-1 isolation attempts from their lymphocytes and sera through reverse transcriptase and p24 antigen detection assays.